1. Field of the Invention
The present invention relates to a vacuum print system. More specifically, the present invention relates to a vacuum print system to print on a work having holes and gaps on its surface, like a printed wiring board.
2. Description of the Prior Art
Several techniques have already been proposed to fill a resin into holes on a plate, such as a printed wiring board, and make its surface flat and even. For example, Japanese Patent No. 3198273 discloses a process to fill a resin into holes, including through holes and non-through holes, by printing on the plate in vacuumed circumstance followed by reducing the vacuum degree of the circumstance in order to introduce the resin deeply into the holes without leaving any unfilled void, by way of the differential pressure.
To print on a printed wiring board in vacuumed circumstance, a printer is usually provided in a sealed chamber. A worktable holding the printed circuit board thereon is carried into the chamber through a door of the chamber, and then, the door is closed before the chamber is evacuated by a vacuum pump and printing is conducted. After printing, the door is opened again and the worktable is carried out from the chamber to take out the printed wiring board.
The printer for a printed wiring board is usually large because it comprises a resin furnishing unit to feed a resin onto a substrate through an apertured plate, and a squeegee unit to run off on the apertured plate pushing the fed resin throughout the apertures onto a substrate. Consequently, the sealed chamber becomes huge to house the large printer. As the capacity of the chamber becomes bigger, it takes longer time to produce a vacuum inside of the chamber after carrying a printed wiring board into, resulting in lower productivity.
Taking the above-described matters into consideration, the present invention has been made. Therefore, an object of the present invention is to provide a vacuum print system with a simple construction, which can attain an excellent productivity at printing on a work having holes and gaps on its surface, like a printed wiring board.
The first aspect of the present invention is a vacuum print system comprising: an outer shell to define an airtight inner space; a printer to print on a work; a worktable to supply the work to the printer; and an air exhaust system to exhaust air in the airtight inner space. The outer shell has a closure door at a ceiling thereof. The printer and the worktable are provided in the airtight inner space, whereas the air exhaust system is connected to the airtight inner space. The worktable is operable to move between a sealing position and a work supplying position. The worktable at the sealing position divides the airtight inner space into two airtight compartments, a first compartment having the closure door, and a second compartment having the printer provided therein and the air-exhaust system connected thereto. The worktable at the work supplying position supplies the work to the printer. Further, the closure door is operable to open to take the work in and out when the worktable is at the sealing position.
The second aspect of the present invention is the vacuum print system of the first aspect, further comprising an additional air exhaust system connected to the airtight inner space at a portion which forms the first compartment when the worktable is at the sealing position. The additional air exhaust system exhausts air from the first compartment when the worktable is at the sealing position and the closure door is closed.
The third aspect of the present invention is the vacuum print system of the first or the second aspect, wherein the worktable divides the first compartment above the second compartment by sealing a linking opening at a bottom of the first compartment, and the worktable is operable to move vertically between the sealing position and a waiting position, and is also operable to move horizontally between the waiting position and the work supplying position. The waiting position is beneath the linking opening and in a horizontal plane common with the work supplying position.
The forth aspect of the present invention is the vacuum print system of any one of the first through third aspects, wherein the worktable comprises a plate-shaped print table to hold the work thereon, and a open-top box shaped frame to support the print table. When the worktable is at the sealing position, a fringe of the frame is pressed against throughout the periphery of the linking opening so as to close the linking opening tightly.
The fifth aspect of the present invention is the vacuum print system of any one of the first through forth aspects, wherein the closure door of the outer shell is in an open-bottom box shape and the open-bottom thereof forms the linking opening.
The advantages of the vacuum print system according to the present invention will be described in the following:
First, the vacuum print system according to the first aspect of the present invention will be mentioned. Prior to carrying a work into the vacuum print system, the airtight inner space defined by the outer shell is vacuumed by the air exhaust system, and divided into two airtight compartments by the worktable at the sealing position. The two compartments are the first compartment having the closure door, and the second compartment having the printer provided therein and the air-exhaust system connected thereto. Then, the closure door of the first compartment is opened and a work is placed onto the worktable, while keeping the vacuum in the second compartment. After closing the closure door, the worktable is moved from the sealing position to the work supplying position, and supplies the work to the printer. With the worktable being moved from the sealing position, the first and second compartments are linked each other and air can flow freely within the airtight inner space. However, air from the atmosphere external to the outer shell is prevented from entering into the airtight inner space because the closure door is closed. Thus, the space where the printer is provided therein (the second compartment) is never opened toward atmosphere. In the case where an additional air exhaust system is connected to the airtight inner space at a portion which forms the first compartment when the worktable is at the sealing position and the closure door is closed, like the vacuum print system of the second aspect of this invention, the first compartment can be exhausted prior to moving the worktable to link the two compartments. In that case, air from the first compartment is also prevented from entering the second compartment. However, if the capacity of the first compartment is much smaller than that of the second compartment, it is not necessary to exhaust air in the first compartment because the volume of air which would enter into the second compartment from the first compartment is relatively small.
Thereafter, printing on to the work is conducted to fill a resin into the holes on the surface of the work. After printing, the worktable is returned to the sealing position. Then, the closure door of the first compartment is opened to take the work out, and if desired, another work will be carried into the system. In this step, the closure door is opened again to take the work out. However, with the second compartment being sealed by the worktable at the sealing position, the space where the printer is provided therein (the second compartment) is never opened toward atmosphere. When the printed work is taken out to atmosphere, a differential pressure would be generated because the printing of the resin into the holes on the surface of the work has been conducted under vacuum. The differential pressure would introduce the printed resin deeply into the holes without leaving any void.
As described above, a work can be carried into and out from the vacuum print system of the first aspect, with keeping the high vacuum degree in the major portion of the airtight inner space where the large printer is provided therein. It means exhausting the entire airtight inner space at each printing of a work is not necessary with this vacuum print system. Therefore, the time required to exhaust air is greatly shortened and the productivity is greatly improved.
Further, according to the vacuum print system of the present invention, a dividing door between the first and second compartments is not necessary because the worktable to carry a work also serves to divide the compartments. Therefore, the vacuum print system of this invention has a simple construction and a large design freedom, and has a great advantage of lower production cost of the whole system.
According to the second aspect of the present invention, the vacuum print system further comprises an additional air exhaust system connected to the airtight inner space at a portion which forms the first compartment. The first compartment can be exhausted while the worktable is at the sealing position prior to moving the worktable to open the linking opening, reducing the burden of the air exhaust system to vacuum the entire airtight inner space.
In the vacuum print system according to the third aspect of the present invention, the worktable divides the first compartment above the second compartment by sealing the linking opening at the bottom of the first compartment. The worktable is operable to move vertically between the sealing position and the waiting position, and is also operable to move horizontally between the waiting position and the work supplying position, tracing a letter xe2x80x9cLxe2x80x9d. According to the third aspect of the present invention, the closure door to take a work into and out from the system can be placed at the side of the printer. Since the printer is usually large, the operation to take a work into and out from the vacuum print system of this construction is much easier than in the case with a vacuum print system having a closure door placed above the printer.
When the closure door is open, the worktable seals the second compartment from atmosphere. There is a possibility of decrease in the surface accuracy of the upperface of the worktable as a permanent deformation caused by the atmospheric pressure. According to the forth aspect of the present invention, the worktable comprises a plate-shaped print table and an open-top box shaped frame to support the print table. With this construction, the frame receives the stress caused by the atmospheric pressure, preventing the plate-shaped print table from being deformed, and keeping the precise surface accuracy of the upperface of the print table.
According to the fifth aspect, the closure door is in an open-bottom box shape and the open-bottom thereof forms the linking opening. The first compartment can be formed only with the closure door and the worktable at the sealing position. The construction of the system can be extremely simplified.